Automatic switch



March 18, 1930. H. F. oBERGFELL 1,750,902

AUTOMATIC SWITCH Herbff ZJWEII Hym- H. F. OBERGFELL AUTOMATIC SWITCH 2 sheets-sheet 2 Filed llarh 5, 1925 InUEnY/Jr Herbz ber 75l! mw HIT- March 18, 1930.

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Patented lVlax'. 18, 1930 UNITED STATES PATENT OFFICE HERBERT F. OBERGFELL, OF RIVER FOREST, ILLINOIS, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO AUTOMATIC ELECTRIC INC., 0F CHICAGO, ILLINOIS, A CORPORATION 0F DELAWARE AUTOMATIC SWITCH Application filed March 5, 1925. Serial No. 13,046.

This invention-relates in' general to auto matic telephone systems, more especially to improvements in the mechanical design of the switchesof such a system.

The invention relates specifically to an improved structure for the non-numerical line switches of an automatic telephone system, and to an improved armature arrangement of such switches and of certain relays in the system. One of the objects of this'invention is the design of an improved line switch of the plunger type that permits ease of manufacture and assembly, simplification of the ad justment and maintenance operations.

A further object of this invention is the adaptionA of 4the armature 'arrangement of this line switch to the structure of a horizontal type automatic relay, forming a simplified two-step relay. l

Other objects and advantages of this in` vention will appear from the detailed specification and claims which follow. y

Referring to the drawings comprising Figs. 1-9, inclusive, Figs. l, 2, 3, 8 and 9 are assembly and detail drawings of the-line switch structure incorporating the features of this invention. Figs. 5, 6 and 7 are details of the improved arm'aturearrangement of my invention adapted to theA horizontal type automat-ic relay. Fig. 4 shows a part of an automatic telephone circuit incorporating the line switch and relay of this invention.

Referring to the drawings more in detail,

Fig. l shows the improved switch completelyl assembled. The well known plunger type line switch, associated with the subscribers line, is shown in detail in the book Automatic Telephone Practice, by Harry E. Hershey, in Fig. 27 on plate 2 of the fourth edition. Among the improvements made in this invention over the standard switch as shown in the reference, is the simplification of the heel piece structure of the line relay designated by 2 in Fig. 1. In the old structure the heel piece of the line relay was a separate member attached to the main frame of the line switch by machine screws. In the present inventionthe heel piece structure. 17 has been formed as a part of the main frame of the switch. A further improvement upon A further improvement in this invention is in regard to the mounting of the main magnet 3 of Fig. 1 of the line switch. In the standard switch of the above reference, the heel piece structure of this magnet was formed L-shaped7 with a short-er portion parallel to the base of the main switch-frame, the core being attached to this latter portion. In this invention the heel piece of the main magnet is formed as a straight projection of the main switch-frame, and the core 9 of the magnet extended and attached directly to the frame of the switch.

In the switch of the above reference, a main spring is attached to the base or the right of the operating magnet. This spring` bears against a roller on the plunger armature in such a manner as to return the plunger armature to its normal position when the operating magnet is deenergized. In the' record the number of times the plunger armature is operated, and results also in a simplified construction of both the switch-frame'l. and plunger armature 4.

'Ihe bridge cut-off armature of the standard switch lies inside and beneath the pull- 'down armature, an arrangement which necessitates a step in the core of the main magnet.

The bridge cut-off armature 5 of this invention lies on the inside and above the pull-down armature 4. The bridge cut-off armature is so shaped that a projection on the end of it extends through an opening in the pull-down armature, an arrangement which makes possible the use of'an ordinary square end core of attachments.

'for the magnet 3. The pull-down armature 4 in addition to being slotted to permit the bridge cut-off armature to work through it is simplified by the rearrangement of the main spring 11 as mentioned above.

In the standard switch of the above reference the jack mounting bracket is a separate member attached tothe main switch frame by a screw. In the simplification of this switch in this invention, the jack mounting bracket 18 of Fig. 2 is formed as an integral part of the main switch frame 1.

l Fig. 2 shows the new switch frame stripped l It will be noted that the frame is formed of one piece of metal with the projections bent at-right angles from the main body of the lframe. The line relay heel piece 17 and the main magnet heel piece 16 are drilled and topped to permit the mounting of their respective armatures and spring assemblies. A projection 1v9of the switch frame supports the back stop screw 10 of Fig. 1 against which the plunger armature 4.

rests when the plunger 6 is under the control of the guide shaft. A designation card holder 10 is held between the projection 19 and the lock nut on the screw 10.

Fig. 3 shows a detail of the pull-down and bridge cut-ofi armature mounting, both armatures being supported on the single bearing pin 15|whicl1 is in turn supported by the mounting bracket 15 which is attached to the heel piece by two screws.

The plunger 6 of the line switch has been improved as shown in Figs. 1, 8 and 9. A rib 20 has been formed in the neck of the plunger to sti'ifen the structure.. A sectional view of a portion of this neck is shown in detail in Fig. 8.

The upper part of the plunger 6 is bent back forming a ange against which the plunger guide shaft rests when the vswitch is in its normal position. This flange 21 is lformed at an angle slightly more than 90 degrees to the faceof the plunger. 'A The angle of this vflange causes the plungerto strike the guide shaft on its outside edge, Fig.v 9, and the flange bends slightly before coming to rest against the guide shaft.` This arrangement absorbs the shockas theplunger returns tof normal,-l

thereby relieving the strain on theplunger bearing pin 22 and theguide shaft, not shown.

F ig. 9, which is a sectional view of the vplunger 6 throu tails of this construction'.

Referring'to Figs. 5 and 6 the armature' ari-an ement-of the line switch shown in Fig. 1 has 'nadapted to a horizontal typeautomatic relay. The main armature 204 Y vis pierced at a point adjacent to the core 209 of the relay and the auxiliary armature 205 ex' tended through this opening. The two armatu es aresupported by the single bearing pin- 21kwhich is attached tothe heeljpiece by ,windingl 1 11, to open-main battery. -T fswitchCiibeing ofthe preselecting type willalways be, standingopposite an-ldle trunk,

ah the axis AA, clearly shows the def means oi the mounting bracket 215 in the manner similar to that on the line switch.

Fig. 7 shows the details of the armature lever 204 and bushing 206. The bushing is made of hard rubber and attached to a projection of the armature lever by an eyelet 207, which extends through the armature. This eyelet is made of phosphor bronze and is so shaped that its back portion 207 forms a residual plate, keeping the armature a Small distance away from the heel piece when in its normal position.

A further advantage of the armature arrangement of this invention lies in the easy manner in which the armature assembly can be assembled on the switch. When properly assembled, the center of the bearing pin 215 is exactly even with the end of the core 209 and the heel piece 201. In assembling, this adjustment is made by lacing the armatures on the heel piece, pus ingthem into their operated position and then tightening the screws which hold the mounting bracket 215' to the heel piece. This same advantage :and method of assembly applies equally' well to the line switch structure. I

Fig. 4 shows a circuit embodying the switch and relay of this invention. This circuit comprises the primary and secondary line switches of any well knownautomatic system, such as that shown in. the applicafrom start ground, over conductor .103,

through springs 13, line conductor 101,

through the telephone, to4 line conductor 102,` through springs 12, through the winding of,v

relay 2 tov grounded negative battery. Re;

`lay 2 energizes over this circuit and at springs M closes a circuit for the pull-down winding,

of thev lineswtch vtraceable from supervisory ground, through springs 1,4, througlh the and, upon the 'energization'rcf the winding. 111, pull-down'armature land bridge cutoi armature 5 willbe attracted, the former to e line cause the plunger to enterthe bank andthe i' latter to 'operate the springs 12 and 13'from their respective resting contacts. When the pull-down varmature 4 operates, the vbank springs of 120, 121, 122 and 123, are forced against their respective vbank contacts, extending, thecircuit to the Asecondary line switch. The loperationv of the bridgecut-oi Tiratura 5 at springs andlB-,opens the for a few circuit of the line relay 2, which relay, being slow to release because of the copper collar on its core, remains in an operated position moments after the current is interrupted in its coil.

The operation of the bank terminals extends thecircuit to the secondary line switch S which is of the post selecting type in which the wipers have no normal position but move in a forward direction only from the trunk terminals on which they were last used. The operation of the bank springs closes a circuit traceable from ground, through spring 158 and' its break contact, conductor 126, bank terminal 123 and its 'associated bank contact, conductor 101, through the subscribers telephone loop to conductor 102, to bank terminals 120, conductor 124, through spring 152 and its break contact, through the upper winding of relay 150 to grounded negative battery. Relay 150 energizes over the above traced circuit, but because the upper winding of this relay is comparatively weak the relay energizes only half way; that is, the armatures 204 and 205, shown in Fig. 5, are attracted until the projection of armature 205 strikes the core 209. With the relay in this positionsprings 154, 155 and 159 make contact'with their associated working contacts, but the other springs remain unchanged at this time. The energization of relay 150 in its first step closes a circuit traceable from ground through spring 159 and its make contact, through spring 157 and its break contact, conductor 125, through bank terminals 121, through the winding 110 of the primary line switch C to grounded negative battery. The winding 110 is energized over this circuit and holds the armature 4 of the line switch .C in operated position after the winding 111 1s deenergized as the relay 2 deenergizes.

The operation of thersecondary line switch S from this point depends upon whether or not the trunk upon which the wipers 160, 161 and 162 are standing is busy at the moment.

`Assume first that it is busy. The wiper 161 will encounter a guarding ground potential,

closing a .circuit for the motor magnet 151 which is traceable from the ground on the contact encountered by the wiper 161, through` spring 153 and its break contact, through spring 155 and its make contact, through springs 159, through the winding of magnet 151 to grounded negative battery. The magnet 151 energizes over this circuit and at springs 159 interrupts its own circuit at thecompletion of the stroke of the armature. The armature then falls back and advances the wipers 160, 161 and 162 onto the next trunk in the well known manner. If that trunk be busy the circuit-for magnet 151 is f again closed and the switch operates as be` .fore to'` take another step,

continuing this operation until an idle trunk is found. Duringgthe trunk hunting operationvthe lower winding of the relay 150 is short circuited, having ground potential connected to both of its terminals through spring 155 and its make contact, and through spring 154 and its make contact, the former being grounded from the grounded trunk terminals encountered by the wiper 161 and the latter from the grounded release trunk conductor 125. When an idle trunk is found no ground potenial will be encountered 161 and the short circuit will be removed from the lower `winding of relay 150. A circuit will then be closed for this winding traceable from grounded release trunk conductor 125, through spring 154 and its make contact, through the lower winding of relay 150, through springs 159, through the motor magnet 151 to grounded negative battery. The relay 150 energizes over the above traced circuit and pulls the armature 204 of Fig. 5 completely against the core, operating the springs 152, 153, 157 and 158 which were not operated upon the first energization of this relay. Magnet 151 is prevented from operating over this circuit b the high resistance of the lower winding ofythe relay 150. Relay 150, upon energizing, extends the callin line through Wipers 161 and 162 to the idle first selector E which switch is seized in the well known manner over conductors 163 and 165 and returns the holding ground over conductor 164 to hold the secondary line switch S and the primary line switch C in their energized positions. The first selector E being seized and protected is ready to receive the impulses transmitted by the calling device of lthe calling station A and operates in response to these impulses to step the wipers 171, 172 and 173 up and around into engagement with the trunk terminals 174,

by the test wiper 175 and 176 leading to the next switch to be used.

When the conversation is completed `and the calling and called parties have replaced their receivers ground is removed from the conductor 164 in the well known manner. and the relay 150 and thewinding 110 are de` energized allowing the-secondary and pri` is attracted, but not Vstrong enough to enerc gize the corel 9 sulliciently to attract the ar- 1 mature 4. lThe bridge cut-off armature 5,

upon being attracted, opens springs 12 and` 13, disconnecting the line relay 2 and the start ground from the called line. The called station A may then be signalled and conversation may take place over the line conductors in the well known manner. Having thus described my invention what I consider new and desire to have protected by Letters Patent is pointed out in the appended claims.

What is claimed is 1. In a telephone system, a relay having a pair of armatures, a core for said relay, both of said armatures rotatable about an axis which lies in the same plane as the faces of the armatures which engage the core of the magnet, and a bracket acting as a bearing for both 'armatures upon which the two are mounted as a'unit and which unit is then attached to the relay.

2. In'a telephone system, a relay having a pair of armatures, a'core for said relay, both of said armatures rotatable about an axis `which lies in the same plane as the faces of jections forming the-heel pieces of the relay of said switch.

4. A switch Vframe comprising a base having projections formed at right an les thereto, the first of said projections orming a mounting plate for mounting'said frame, the

second projection forming a heel Apiece upon which are mounted the armature Vand spring assembly of one of the relays of said switch, a second heel piece formed as a projection of mounting plate and being at right angles,

thereto and in a plane parallel to the plane of said first heel piece, said frame and pro- I jections being 'ofl a unitary structure so deof said armatures rotatable about an axis which lies in the same plane as the faces of the armature which engage said magnet core, and a bracket acting as a bearing for both armatures upon which the two are mounted as a Aunit and which unit is then attached to l said heel piece.

7. In a telephone system, a relay heel piece having a magnet core and springs mounted thereon, two armatures for said relay, both of said armatures rotatable about an axis which 'lies in the same plane as the faces of the armature which engage said magnet core, and a bracket to which the rod which forms the bearing for both of said armatures isriveted with both armatures rotatably mounted thereon as a unit, which unitis then attached to said heel piece.

In witness whereof, I hereunto subscribe my name this 2d day of March, A. D. 1925. HERBERT F. OBERGFELL.

signed as to permit its being formed from.

sheet metal stock. .l 5.1 A switchv frame comprising a base, a

projection of'said base disposedgat .right angles vthereto Aand forming a mounting plate by means of which said frame may be mounted on a 'suitable sup ort, a second projection of said base dispose at rightangles'thereto projection of said mounting plate disposed at right angles thereto and arallel to said second projection, said secon and third me'ntioned projections' forming heell piece structures for mounting the re ay armatures and spring assemblies.'V A- A Y 6. In a telephone system, a relay heel piece having a magnet core and springs mounted thereon, two armatures for 'said relay, both and at right angles to said mounting plate, a 

